Stages of Child Development From Infancy to Adolescence

From infancy to adolescence, children grow physically, mentally and socially into mature beings. During the first 18 years of life, brain functioning expands, enabling children to develop from simple understandings at birth to complex levels of thinking during adolescence. Muscles, bones and internal organs become fully functioning. Personality and social skills begin as simple smiles and develop into unique, individual identities. What an exciting process for parents to watch and marvel over as your sweet baby grows into an adult!

Infancy and Toddlerhood

According to Robert S. Feldman, Dean of Social and Behavioral Sciences at the University of Massachusetts Amherst, children develop more rapidly during their first three years than any other time in life. Infants begin at an average weight of seven pounds and increase to 30 pounds by the age of three. Feldman notes that babies develop motor skills from learning to roll over at three months to jumping in place at two years old. Mental improvements start with your baby's laughter at six weeks, mimicking sounds at eight months, and saying their first words at a year old. By the time your child is three years old, he or she will speak in sentences and ask many questions. Feldman states that attachment is an important social development during infancy. Babies who successfully form a bond between themselves and their caregiver learn to feel secure and to trust others.

Preschool Years

From ages three to six, it may seem like your child is constantly saying, "Mommy, watch me do this!" According to, preschoolers stay busy honing their new physical skills, like running, jumping, catching and throwing. Mentally, children become conscious of their own thoughts and understand what others around them think. Feldman explains other important cognitive milestones are computing simple math problems and learning how to use grammatical rules in speech. During this period, your child also develops awareness of maleness and femaleness, which is greatly influenced by parental guidance and social media, like television and children's books.

Middle Childhood

For many children, the elementary school years are a time of academic achievement, involvement in sports, development of musical talent, and awareness of individual personality traits. According to the National Network for Child Care, or N.N.C.C., kids in middle childhood control their larger muscles better than their smaller ones. Mentally, children can comprehend rules in games and think ahead to figure things out. In middle childhood, the N.N.C.C. recommends that parents set clear limits with consequences and offer help and guidance when needed.


According to, adolescents grow almost as rapidly as babies to reach their adult height by the end of their teen years. You are also sure to notice your son's voice deepening or that your daughter is shaving her legs. Feldman points out that these are outer signs of inner sexual organs maturing. Teenagers advance in their reasoning and debating skills, often trying them out on their parents. While teens are the size of an adult and have the capability to talk like one, Feldman reminds parents that adolescents are subject to egocentric thinking, or to put it another way, they believe that they are bulletproof. Social activities and the advice of friends often take the place of family time and parental guidance. Feldman remarks that, in the end, an adolescent's individual identity is a culmination of parental and peer influences, along with life experiences.